Papers by Author: Tadashi Kokubo

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Authors: Mitsuru Takemoto, Shunsuke Fujibayashi, B. Otsuki, Tomiharu Matsushita, Tadashi Kokubo, Takashi Nakamura
Abstract: Generally, characterizations of pore structures of porous biomaterials are mainly based on 2-dimensional (2-D) analysis using cross sectional micrographs. However, interconnectivity of each pore may be more important factor, when tissue ingrowth into deeper pores is considered. In this paper, using micro-CT imaging with 3-D image processing software, analyses of porous material based on 3-demensional (3-D) geometrical considerations were successfully performed. Plasmasprayed porous titanium implant (PT) and four types of sintered porous titanium implants (ST50- 200, ST50-500, ST70-200, and ST70-500) that possess different porosities (50% and 70%) and pore sizes (200-500+m and 500-1500+m) were analyzed in this study. A micro focus X-ray computed tomography system was employed to acquire microstructural information from the porous implants. Using 3-D image processing software, we performed three types of 3-D analysis including detection of the dead space (% dead pore), analysis of interconnectivity by blocking the narrow pore throat with caliber less than 52 +m (% pore with narrow throat) and analysis of material construct by contracting thin strut with thickness less than 52 +m (% construct with thin strut). ST50S and ST50L possessed interconnected porous structure with thicker strut; however, pore throat was considered to be relatively narrow. On the other hand, PT implant possesses favorable interconnectivity despite its’ low porosity; however, relatively thin strut indicate the structural disadvantage for mechanical property. These results suggest that the 3-D analysis of pore and strut structure using micro focus X-ray computed tomography and 3-D image processing software will provide effective information to develop porous implant.
1095
Authors: S. Shinzato, Takashi Nakamura, Tadashi Kokubo
365
Authors: S. Shinzato, Takashi Nakamura, Koji Goto, Tadashi Kokubo
Abstract: Alumina powder containing δ , δ crystal phases (designated δAP) showed osteoconductivity. δAP was manufactured by fusing pulverized alumina powder and quenching it. The purpose of the present study was to evaluate osteoconductivity of δAP using rat tibiae. Alumina powder containing αcrystal phase (designated αAP) was used as a reference material. These two types of alumina powder were packed into the intramedullary canals of rat tibiae to evaluate osteoconductivity, as determined by an affinity index. Rats were sacrificed at 4 and 8 weeks after surgery. The affinity index, equal to the length of bone in direct contact with the powder surface expressed as a percentage of the total length of the powder surface, was calculated for each alumina powder at each interval. At 4 and 8 weeks, the affinity indices for δAP were significantly higher than those for αAP. For both δAP and αAP, there were no significant differences between the values for 4 and 8 weeks. This study revealed that the osteoconductivity of δAP was due to the alumina’s δcrystal phases. δAP shows promise as a basis for developing a osteoconductive biomaterial.
789
Authors: Ayako Oyane, Masahiko Minoda, T. Miyamoto, Kazuki Nakanishi, Kawashita Masakazu, Tadashi Kokubo, Takashi Nakamura
713
Authors: Naoshi Ozawa, Yoshihiro Ideta, Takeshi Yao, Tadashi Kokubo
71
Authors: Naoshi Ozawa, Yoshihiro Ideta, Takeshi Yao, Tadashi Kokubo
127
Authors: Noboru Miyata, K. Fuke, Qi Chen, Kawashita Masakazu, Tadashi Kokubo, Takashi Nakamura
117
Authors: J.A. Juhász, Kawashita Masakazu, Noboru Miyata, Tadashi Kokubo, Takashi Nakamura, Serena Best, William Bonfield
437
Authors: Masanobu Kamitakahara, Kawashita Masakazu, Noboru Miyata, Hyun Min Kim, Tadashi Kokubo, Chikara Ohtsuki, Takashi Nakamura
521
Authors: Masanobu Kamitakahara, Kawashita Masakazu, Noboru Miyata, Tadashi Kokubo, Takashi Nakamura
633
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